In this editorial, we will introduce the contributions to the Special Issue entitled “Measuring Open Access Uptake: Databases, Metrics, and International Comparisons.” The contributions to this Special Issue explore the methods and metrics that are used to assess open access (OA) uptake across disciplines and regions, a crucial topic considering the growing push by several research institutions worldwide to achieve 100% OA. We will discuss the impact of OA on scholarly publishing, focusing on how economic factors and discipline-specific practices shape its adoption. Additionally, we will examine the transformation of OA models, the citation benefits of a hybrid OA model, and regional perspectives. Our analysis identifies key challenges and disparities in OA adoption and suggests future directions for achieving sustainable and equitable access to research.